a superb article about the feral cat "Trap, Neuter, Release" programs that are subsidizing feral cats, making them last longer as bird killers without reducing their numbers ANYWHERE. It's a great article which I strongly recommend.
My personal cat, Kasey, came from one of those ridiculous TNR programs--I took her in because I couldn't bear to watch her killing birds. She's very happy indoors. Those cats that cannot adapt to indoor life should be caged or humanely euthanized. Period.